This disclosure relates to a connection plug for connecting an ignition coil to a spark plug.
The connection plug known from DE 10 2011 082 231 A1 has an electric line in the form of a helical spring that is surrounded by a protective hose. The protective hose is surrounded by a protective pipe which, at an end portion towards the spark plug, has an inwardly oriented projection that engages in a groove on the outside of the protective hose so that the protective hose is retained in the protective pipe in a positive-locking manner. The groove at the outside of the protective hose is formed by two radial circumferential projections on the inside of the protective hose which are arranged at an axial distance from one another. For retaining the protective hose at the spark plug there is provided an additional pin that is pressed into a corresponding through-hole in the protective hose and the protective pipe and thus achieves a locking between the protective hose and the protective pipe. If the protective hose needs to be pulled out of the protective pipe, the pressed-in pin first has to be removed.
A positive-locking connection between the protective hose and the protective pipe, on the one hand, has to be flexible enough so that the protective hose can be inserted into the protective pipe and, on the other hand, has to generate enough retention force so that the protective hose cannot unintentionally be pulled out of the protective pipe.